RESEARCH: Ending Endophyte Toxins

FAYETTEVILLE, Ark. -- University of Arkansas Division of Agriculture scientists are studying means of taking the toxic bite out of endophyte-infested fescue in Arkansas pastures.

"Cattle producers in Arkansas and other states rely heavily on tall fescue because it is easily established and very hardy," said Ed Piper, UA animal physiologist. "Tall fescue contains a fungal endophyte that produces alkaloids that are toxic to cattle and cost Arkansas cattle producers $50 million a year. Wildlife populations also are affected by the presence of this endophyte."

Animal and plant scientists at the Arkansas Agricultural Experiment Station are approaching the problem form two sides, studying the promise of non-toxic endophytes and seeking clues to breeding endophyte-tolerant cattle.

Chuck West, UA forage physiologist, said endophytes benefit the fescue, protecting them from drought stress and various insect and other pests. Use of endophyte-free fescue will help with animal production, but these pasture stands tend to thin out.

Piper and West have identified endophyte-infected fescue plants that do not produce the toxic alkaloids. These endophytes were isolated and placed in an adapted forage variety of endophyte-free fescue.

"The endophyte-infested, nontoxic variety was planted at two sites to use in grazing trials," Piper said. "Two years of trials revealed steers grazing the non-toxic endophyte-infested fescue gained as well as steers grazing endophyte-free fescue."

He said these cattle did not show symptoms of endophyte toxicosis, including elevated body temperatures or long, rough hair coats. West said the new endophytes seem to promote grass persistence, much like their toxic relatives. Further tests under a wide range of conditions are being conducted to determine non-toxic fescue's ability to withstand drought and pest tolerance.

Piper said non-toxic varieties of fescue can increase calving rates from 70 percent to 90 percent and calf weaning weights by 50 pounds. Non-toxic fescue also should be a high-quality sustainable forage for dairy farmers and horse producers and more environmentally friendly to wildlife.

Seed for this non-toxic forage may be available for farmers in two to three years, West said.